Latest figures show that more than half of the UK population – 65% of men and 58% of women – are overweight or obese.

When we eat and drink more calories than we use up, our bodies store the excess as body fat. If this continues, over time we may become overweight and can become obese. Being overweight or obese can increase the risk of type 2 diabetes, heart disease, stroke and some cancers.

Many adults in the UK need to lose weight, and to do this they need to eat and drink fewer calories. Combining these changes with increased physical activity is the best way to achieve a healthier weight.

The term calorie is commonly used shorthand for kilocalorie. On food packets you will find this written as kcal. Kilojoules (kJ) are the metric measurement of calories, and you’ll see both kJ and kcal on nutrition labels – 4.2kJ is equivalent to approximately 1kcal.

How much should you eat?

Our bodies need energy to keep us alive and our organs functioning normally. The amount you need to eat for your body to do this depends on a range of factors, including your size, age, gender and how physically active you are.

To maintain a stable weight, the energy we put into our bodies must be the same as the energy we use up through normal body functions and physical activity. An important part of a healthy diet is eating the right amount of calories; balancing the energy you put into your body with the energy you use.

As a guide, men need around 2,500kcal (10,500kJ) a day to maintain a healthy body weight, and women need around 2,000kcal a day (8,400kJ).

If you need to lose weight, aim to lose about 0.5-1kg (1-2lb) a week until you reach a healthy weight for your height. You should be able to lose this amount if you eat and drink about 500-600kcal fewer a day than you need.

You can find out whether you are a healthy weight by using the BMI calculator. If you are overweight, the healthy weight calculator will give you a personalised suggested calorie range.

If you are very physically active because of your job or you do a lot of exercise, you may need more calories to maintain a healthy weight. If you do very little physical activity – for example, you are housebound – or if you are overweight or obese, you may need fewer calories.

A healthy diet is not only about eating the right amount. It also means eating a wide range of foods to ensure you get all the nutrients you need. You can still eat less when following a balanced diet. Learn more about a balanced diet in the Eatwell Guide.

How much are you eating?

Most of us are eating and drinking more than we need, and we often think we are more active than we actually are.

It's estimated that the average adult has 200-300 more calories than they need every day. This might not sound much, but over time it will cause significant weight gain.

Foods and drinks that are high in fat or sugar can contain lots of calories, and eating or drinking these often or in large amounts can make it easy to have more calories than you need.

If you are overweight or obese, think about where your extra calories are coming from and make changes to your diet to reduce the number of calories you consume.

In England in 2011:

65% of men and 58% of women were overweight or obese.

The average (mean) height for men was 175.3cm (5ft 9in) tall while the average height for women was 161.6cm (5ft 3in) tall.

The average (mean) weight for men was 83.9kg, while the average weight for women was 71kg.

Use the BMI calculator on this page to see if you're a healthy weight for your height.

How you can eat less

You can reduce the number of calories you eat by making healthier choices when it comes to food and drink.

It's not just foods: drinks can be high in calories, too. To consume fewer calories, you should choose drinks lower in fat and sugar, or have smaller amounts of high-calorie drinks less often. Don't forget that alcohol can also be high in calories.

As well as choosing foods and drinks lower in fat and sugars, also think about reducing the size of your portions. Research suggests we tend to eat more when we are served more, even when we don't need the extra calories.

When serving yourself food at home, resist filling your plate, and think about whether you're really hungry before having an extra helping. When eating out, avoid supersizing or choosing large portions of food or drink.

Knowing the calorie content of different foods and drinks can be useful when it comes to achieving or maintaining a healthy weight. It can help us keep track of the amount of energy we put into our bodies and ensure we are not eating too much.

The calorie content of many foods and drinks is on the packaging as part of the nutrition label. You can look at the calorie figure to assess how a particular food or drink fits into your daily intake. The calorie checker on this page can tell you how many calories are in a wide variety of foods and drinks.

Swap sugary fizzy drinks for diet versions with low or no calories. Even better, swap some soft drinks for sparkling water with a slice of lemon.

Swap the frying pan for the grill when cooking meat – you don't need to add any oil.

Swap creamy or cheesy sauces for tomato or vegetable-based sauces on your pasta or meat and fish dishes.

Choose wholegrains, including wholemeal and wholegrain bread, or wholegrain breakfast cereals. Wholegrain foods contain more fibre and other nutrients. We also digest wholegrain foods more slowly, so they can help make us feel fuller for longer.

Swap a cake or biscuits for a currant bun or some malt loaf – plain or with reduced-fat spread.

Read food labels: they can help you choose foods that are lower in calories, as well as lower in saturated fat and sugars.

Remember to combine eating fewer calories with more physical activity to gradually lose weight and help you keep it off.

More healthy eating advice

If you currently eat too much, making changes towards a healthy, balanced diet will also help you reduce the number of calories you eat and drink, as well as help make sure you get all the nutrients you need.

You can learn about the foods we need to eat for a balanced diet in the Eatwell Guide.